This invention relates to evaporative pattern assemblies and, more particularly, to evaporative pattern assemblies for preventing distortion of a pattern during aging or sand compaction around and in the pattern.
Evaporative pattern assemblies for use in sand casting have previously been provided with bonded sand cores that completely filled cavities disposed in locations where sand would not flow during sand compaction in and around the pattern. The invention disclosed herein is provided for a different purpose and only partially fills the cavity so that sand can flow into the cavity.
Distortion of foam evaporative patterns have customarily been controlled by molding the patterns with foam pieces that were provided solely for reinforcement. When such assemblies were used to produce a casting, metal would remain in the place of the reinforcement foam pieces. Such cast reinforcements increase the weight of the casting and the amount of metal used, and must be removed in instances where the cast metal reinforcements cannot be left in the casting. This invention alleviates the problems caused by such reinforcement foam pieces.
Attention is directed to the following U.S. patents relating to pattern casting:
______________________________________ Patentee U.S. Pat. No. Issued ______________________________________ Cole 4,396,054 August 2, 1983 Peras 3,041,689 July 3, 1962 ______________________________________